title: Radio-sensitization of human leukaemic MOLT-4 cells by DNA-dependent protein kinase inhibitor, NU7441.
abstract: We studied the effect of pre-incubation with NU7441, a specific inhibitor of DNA-dependent protein kinase (DNA-PK), on molecular mechanisms triggered by ionizing radiation (IR). The experimental design involved four groups of human T-lymphocyte leukaemic MOLT-4 cells: control, NU7441-treated (1 μM), IR-treated (1 Gy), and combination of NU7441 and IR. We used flow cytometry for apoptosis assessment, Western blotting and ELISA for detection of proteins involved in DNA repair signalling and epifluorescence microscopy for detection of IR-induced phosphorylation of histone H2A.X. We did not observe any major changes in the amount of DNA-PK subunits Ku70/80 caused by the combination of NU7441 and radiation. Their combination led to an increased phosphorylation of H2A.X, a hallmark of DNA damage. However, it did not prevent up-regulation of neither p53 (and its phosphorylation at Ser 15 and 392) nor p21. We observed a decrease in the levels of anti-apoptotic Mcl-1, cdc25A phosphatase, cleavage of PARP and a significant increase in apoptosis in the group treated with combination. In conclusion, the combination of NU7441 with IR caused increased phosphorylation of H2A.X early after irradiation and subsequent induction of apoptosis. It was efficient in MOLT-4 cells in 10× lower concentration than the inhibitor NU7026. NU7441 proved as a potent radio-sensitizing agent, and it might provide a platform for development of new radio-sensitizers in radiotherapy.
authors.affiliation: Department of Radiobiology, Faculty of Health Sciences in Hradec Kralove, University of Defence in Brno, Brno, Czech Republic, tichy@pmfhk.cz.
authors.forename: Ales
authors.initials: A
authors.lastname: Tichy
authors.forename: Kamila
authors.initials: K
authors.lastname: Durisova
authors.forename: Barbora
authors.initials: B
authors.lastname: Salovska
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Pejchal
authors.forename: Lenka
authors.initials: L
authors.lastname: Zarybnicka
authors.forename: Jirina
authors.initials: J
authors.lastname: Vavrova
authors.forename: Natalie A
authors.initials: NA
authors.lastname: Dye
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Sinkorova
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002867:Chromones / Q000494:pharmacology*; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects / Q000528:radiation effects; D051747:DNA-Activated Protein Kinase / Q000037:antagonists & inhibitors*; D006657:Histones / Q000378:metabolism; D006801:Humans; D007938:Leukemia / Q000473:pathology*; D009025:Morpholines / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects / Q000528:radiation effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011836:Radiation Tolerance / Q000187:drug effects*; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects; D013997:Time Factors
chemical_list: C499693:8-dibenzothiophen-4-yl-2-morpholin-4-yl-chromen-4-one; D002867:Chromones; C468783:H2AX protein, human; D006657:Histones; D009025:Morpholines; D047428:Protein Kinase Inhibitors; D011838:Radiation-Sensitizing Agents; D051747:DNA-Activated Protein Kinase